Function arrIndexOf

The arrIndexOf() method returns the first index at which a given element can be found in the array, or -1 if it is not present. arrIndexOf() compares searchElement to elements of the Array using strict equality (the same method used by the === or triple-equals operator).

Example

const array = [2, 9, 9];
arrIndexOf(array, 2);     // 0
arrIndexOf(array, 7);     // -1
arrIndexOf(array, 9, 2);  // 2
arrIndexOf(array, 2, -1); // -1
arrIndexOf(array, 2, -3); // 0

let indices: number[] = [];
const array = ['a', 'b', 'a', 'c', 'a', 'd'];
const element = 'a';
let idx = arrIndexOf(array, element);
while (idx !== -1) {
  indices.push(idx);
  idx = arrIndexOf(array, element, idx + 1);
}
console.log(indices);
// [0, 2, 4]

function updateVegetablesCollection (veggies, veggie) {
    if (arrIndexOf(veggies, veggie) === -1) {
        veggies.push(veggie);
        console.log('New veggies collection is : ' + veggies);
    } else {
        console.log(veggie + ' already exists in the veggies collection.');
    }
}

let veggies = ['potato', 'tomato', 'chillies', 'green-pepper'];

updateVegetablesCollection(veggies, 'spinach');
// New veggies collection is : potato,tomato,chillies,green-pepper,spinach
updateVegetablesCollection(veggies, 'spinach');
// spinach already exists in the veggies collection.

// Array Like
let arrayLike = {
  length: 3,
  0: "potato",
  1: "tomato",
  2: "chillies",
  3: "green-pepper"  // Not checked as index is > length
};

arrIndexOf(arrayLike, "potato"); // 0
arrIndexOf(arrayLike, "tomato"); // 1
arrIndexOf(arrayLike, "chillies"); 2
arrIndexOf(arrayLike, "green-pepper"); // -1
  • arrIndexOf<T>(theArray, searchElement, fromIndex?): number

  • Type Parameters

    • T

      Identifies the type of array elements

    Parameters

    • theArray: ArrayLike<T>

      The array or array like object of elements to be searched.

    • searchElement: T

      The element to locate in the array.

    • OptionalfromIndex: number

      The index to start the search at. If the index is greater than or equal to the array's length, -1 is returned, which means the array will not be searched. If the provided index value is a negative number, it is taken as the offset from the end of the array. Note: if the provided index is negative, the array is still searched from front to back. If the provided index is 0, then the whole array will be searched. Default: 0 (entire array is searched).

    Returns number

    The first index of the element in the array; -1 if not found.

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